Do you have to have a reg. on your tank when it's sent in for re-hydro?

[TheTramp]

I know that they take off the reg when doing a hydro test but do you need to send them your tank with a reg on it?

I've got two tanks that need to be re-hydroed but I can use their regs on other tanks I've got. Will there be a problem if I just send in the tanks?

[Dayspring]

I know most places actually charge you to take them off. AFAIK, you can send the tank in solo.